CNO cycle

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The CNO cycle is a set of nuclear-fusion reactions in which carbon, nitrogen, and oxygen nuclei act as catalysts for converting hydrogen into helium. The overall energy-producing result is similar to the proton–proton chain, but the intermediate reactions are different.

The cycle begins when a carbon-12 nucleus captures a proton and proceeds through a sequence of proton captures and beta decays. After a complete cycle, the original carbon nucleus is restored while four protons have effectively been converted into one helium-4 nucleus.

The rate of the CNO cycle is strongly dependent on temperature. It contributes only a small part of the Sun's energy but dominates hydrogen burning in stars more massive and hotter than the Sun.

Variants of the cycle involve different isotopes and reaction branches. Measurements of solar neutrinos produced by the CNO cycle provide evidence about fusion conditions and the abundance of carbon, nitrogen, and oxygen in the solar interior.

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• Source / publisher: Wikipedia
• URL type: WWW
• Credits: Wikipedia
• URL: https://en.wikipedia.org/wiki/CNO_cycle